Herbicidal composition and method



3,333,946 Patented Aug. 1, 1967 free 3,333,946 HERBllClDAL COMkOSlTlONAND METHDD Sidney B. Richter, Chicago, and Alfred A. Levin, Skokie,

lll., assignors to Velsicol Chemical Corporation, Chicago, lll., acorporation of Illinois No Drawing. Griginal application May 13, 1964,Ser. No. 367,224. Divided and this application Aug. 31, 1966, Ser. No.576,246

10 Claims. (Cl. 71100) This application is a division of our co-pendingapplication Ser. No. 367,224, filed May 13, 1964, now abandoned.

This invention relates to the production of new pesticidal compositionsof matter. More specifically, this invention relates to new chemicalcompounds of the formula group but still having one -C(O)-Cl jected toalcoholysis with methanol.

The reactions discussed above are ordinarily carried group can be suboutin the presence of suitable inert solvents. The tern peratures at whichthe reactions can be carried out are not critical. Generally,temperatures of from about normal room temperature to about the normalrefiux temperature of the reaction mixture are preferred. While thereactions are normally carried out at atmospheric pressure, suborsuperatmospheric pressures can also be used. The crude reaction productscontaining the new compounds of this invention are often pure enough forpesticidal use as such; but compounds can be purified, if desired, byany of the recognized techniques known to the .art, such as fractionaldistillation, crystallization from suitable solvents, or chromatography.

The maner in which new compounds of this invention can be prepared isillustrated in the following examples, in

1 which all temperatures are in degrees centigrade.

Example ].Preparatin of S-is0pr0pyl ester of 4-thi0-carbon-2,3,5,6-tetrachl0r0benzoyl chloride An aqueous solution (66 g.)of the sodium salt of isopropyl mereaptan (0.16 mol) was added withrapid stirring to a solution of 2,3,5,6-tetrachloroterephthaloylchloride (30 g.; 0.08 mol) in ml. of dioxane in a 250 ml., round bottom,3-necked flask fitted with a mechanical stirrer and reflux condenser.The mixture was stirred overnight at room temperature, filtered throughmagnesium sulfate, and allowed to stand. The solvent was then stipped invacuo to give an oil. The oil was the desired ester, S- isopropyl esterof 4-thiocarboxy-2,3,5,6-tetrachlorobenzoyl chloride.

Example 2.Preparati0n of methyl S-isopropyl 2,3,5,6-

tetrachloromonothioterephthalate The S-isopropyl ester of4-thiocarboxy-2,3,5,6-tetrachlorobenzoyl chloride was allowed to standand solidify. The solid was then dissolved in methanol, heated 'atreflux for several hours, and the solution was cooled. The solid whichprecipitated was filtered off and dried. The solid was recrystallizedfrom heptane and dried to give methyLS-isopropyl2,3,5,6-tetrachloromonothioterephthalate, M.P. 117-19 C.

The following are some typical examples of other tetrahaloterephthaloylchlorides which can be used as starting materials in the mannerdescribed in Examples 1 and 2:

Example 3.2,3,5,6-tetrabromoterephthaloyl chloride Example4.-2,3,5,6-tetraflu0r0terephthaloyl chloride Example 5.2,3,5,6-tetraiodoterephthaloyl chloride When the abovetetrahaloterephthaloyl chlorides are used as starting materials inExamples 1 and 2, the following compounds useful in the method ofcontrol of this invention are obtained, in respective order:

Example 6.Methyl-S-isopropyl-2,3,5,6- tetrabromomonoterephthalateExample 7 .M ethy l-S -is0pro py l-2,3 ,5 ,6- tetralfluoromonoterephthalate Example 8.Methyl-S-isopropyl-Z,3,5,6-tetraiodomonoterephzhalate For practical use as herbicides, thecompounds of this invention are generally incorporated into herbicidalcompositions which comprise an inert carrier and a herbicidally toxicamount of such a compound. Such herbicidal compositions, which areusually known in the art as formulations, enable the active compound tobe applied conveniently to the site of the weed infestation in anydesired quantity. These compositions can be solids such as dusts,granules, or wettable powders; or they can be liquids such as solutionsor emulsifiable concentrates.

For example, dusts can be prepared by grinding and blending the activecompound with a solid inert carrier such as the tales, clays, silicas,pyrophyllite, and the like. Granular formulations can be prepared byimpregnating the compound, usually dissolved in a suitable solvent, onto and into granulated carriers such as the attapulgites or thevermiculites, usually of a particle size range of from about 0.3 to 1.5mm. Wettable powders, which can be dispersed in water to any desiredconcentration of the active compound, can be prepared by incorporatingwetting agents into concentrated dust compositions.

In some cases the active compounds are sufficiently soluble in commonorganic solvents such as kerosene or xylene so that they can be useddirectly as solutions inv ionic or mixtures of nonionic with anionicsurface-active agents.

A typical herbicidal composition according to this invention isillustrated by the following example, in which the quantities are inparts by weight.

Example 9.Preparatin of a dust Methyl S isopropyl 2,3,5,6tetrachloromonothioterephthalate Powdered talc 90 The above ingredientsare mixed in a mechanical grinder-blender and are ground until ahomogeneous, free-flowing dust of the desired particle size is obtained.This dust is suitable for direct application to the site of the weedinfestation.

The herbicides of thi invention can be applied in any manner recognizedby the art. The concentration of the new compounds of this invention inthe herbicidal compositions will vary greatly with the type offormulation and the purpose for which it is designed, but generally theherbicidal compositions will comprise from about 0.05 to about 9.5percent by weight of the active compounds of this invention. In apreferred embodiment of this invention, the herbicidal compositions willcomprise from about 5 to about 75 percent by weight of the activecompound. The compositions can also comprise such additional substancesas other pesticides, spreaders, adhesives, stickers, fertilizers,activators, synergists, and the like.

Weeds are undesirable plants in their growing where they are not wanted,having no economic value, and interfering with the production ofcultivated crops or with the welfare of livestock. Many types of weedsare known, including annuals such as pigweed, lambs-quarters, yellowfoxtail, crabgrass, wild mustard, Frenchweed, ryegrass, goose grass,chickweed, and smartweed; biennials such as wild carrot, great burdock,mullein, round-leaved mallow, blue thistle, bull thistle, hounds-tongue,moth mullein, and purple star thistle; or perennials such as whitecockle, perennial ryegrass, quackgrass, Johnson grass, Canada thistle,hedge bindweed, Bermuda grass, sheep sorrel, field chickweed, and wintercress. Similarly, such weeds can be classified as broad-leaf or grassyweeds. It is economically desirable to control the growth of such weedswithout damaging beneficial plants or livestock.

The new compounds of this invention are particularly valuable for weedcontrol because they are toxic to many species and groups of weeds.while they are relatively nontoxic to many beneficial plants. The methodof this invention for the control of weeds comprises contacting saidweeds with a herbicidal composition comprising an inert carrier and asthe essential active ingredient, in a quantity which is herbicidallytoxic to said Weeds, a compound of this invention. The exact amount ofcompound required will depend on a variety of factors, including thehardiness of the particular weed species, weather, method ofapplication, the kind of beneficial plants in the same area, and thelike. Thus, while the application of up to only about one or two ouncesof an active compound per acre may be suificient for good control of alight infestation of weeds growing under adverse conditions, theapplication of one pound or more of active compound per acre may berequired for good control of a dense infestation of hardy weeds growingunder favorable conditions.

The herbicidal toxicity of the new compounds of this invention can beillustrated by many of the established testing techniques known to theart. For example, soil samples seeded with various weeds were sprayedwithin 24 hours with aqueous emulsions of the test compounds. After thesprays were applied to the soil, the containers were maintained undergreenhouse conditions for -20 days. The plants were then observed forinjury, and the degree injury was rated as follows: 0=no injury;

l,2=slight injury; 3,4:moderate injury; 5,6:moderately severe injury;7,8,9=severe injury; l0=death. In these experiments, the product, methylS-isopropyl-2,3,5,6- tetrachloromonothioterephthalate, at the rate ofonly 2 lbs/acre, caused injury rated at 9 on crabgrass, foxtail and wildoats. This latter weed is especially troublesome in the cultivation ofwheat, and therefore it is particularly significant that the subjectcompound was completely nontoxic to wheat at dosages as high as 8lbs/acre.

Similarly, post-emergence tests were carried out by spraying the testcompounds on the foliage of weeds which had attained a prescribed size.The sprayed plants were maintained under greenhouse condition for 13days, after which the degree of injury was rated on the same scale asdescribed above. In these tests, the compound methylS-isopropyl-2,3,5,6-tetrachloromonothioterephthalate caused injury ratedat 9 on barnyard grass and 8 on crabgrass when used at a rate equivalentto 8 lbs./ acre.

We claim:

1. A herbicidal composition which comprises an inert carrier and aherbicidally toxic amount of a compound of the formula wherein X ishalogen.

2. A composition of claim 1 wherein the compound is methyl S-isopropyl2,3,5,6-tetrachloromonothioterephthalate.

3. A composition of claim 1 wherein the compound is methyl S-isopropyl2,3,5,6-tetrabromomonothioterephthalate.

4. A composition of claim 1 wherein the compound is methyl S-isopropyl2,3,5,6-tetrafluoromonothioterephthalate.

5. A composition of claim 1 wherein the compound is methyl S-isopropyl2,3,5,6-tetraiodomonothioterephthalate.

6. A method for the control of undesirable plant life which comprisesapplying to the locus of said undesirable plant life, in a quantitywhich is herbicidally toxic to said undesirable plant life, a herbicidalcomposition of claim 1.

7. A method for the control of undesirable plant life which comprisesapplying to the locus of said undesirable plant life, in a quantitywhich is herbicidally toxic to said undesirable plant life, a herbicidalcomposition of claim 2.

8. A method for the control of undesirable life which comprises applyingto the locus of said undesirable plant life, in a quantity which isherbicidally toxic to said undesirable plant life, a herbicidalcomposition of claim 3.

9. A method for the control of undesirable plant life which comprisesapplying to the locus of said undesirable plant life, in a quantitywhich is herbicidally toxic to said undesirable plant life, a herbicidalcomposition of claim 4.

10. A method for the control of undesirable plant life which comprisesapplying to the locus of said undesirable plant life, in a quantitywhich is herbicidally toxic to said undesirable plant life, a herbicidalcomposition of claim 5.

References Cited UNITED STATES PATENTS 3,201,220 8/1965 Harris et a1.71-2.6

FOREIGN PATENTS 1,265,053 5/1961 France.

LEWIS GO'ITS, Primary Examiner.

JAMES O. THOMAS, JR., Examiner.

1. A HERBICIDAL COMPOSITION WHICH COMPRISES AN INERT CARRIER AND A HERBICIDALLY TOXIC AMOUNT OF A COMPOUND OF THE FORMULA 